Switching device having electro-magnetic means for increasing effective contact pressure

ABSTRACT

A switching device comprising a pair of bent circuit members made of flexible conductive material and arranged parallel in close proximity to each other, one of which has one of its ends electrically connected in abutting relationship to one end of at least one movable member of a pair of circuit switching electrodes and the other of which is pressed downward to the other end of said movable electrode by means of its operating mechanism, whereby there is generated in the paired bent circuit members a repulsive force opposing that occurring in said two electrodes at the time of conduction.

United States Patent Toshihlko Yoshlo Tokyo, Japan May 27, 1969 Oct. 19, 1971 Tokyo Shibaura Electric Co., Ltd. Kawasaki-shi, Japan May 30, 1968 Japan Inventor Appl. No. Filed Patented Assignee Priority SWITCHING DEVICE HAVING ELECTRO- MAGNETIC MEANS FOR INCREASING EFFECTIVE CONTACT PRESSURE Claims, 2 Drawing Figs.

US. Cl 200/144 B,

[51] Int. Cl

IIOIh 33/66 Field of Search 200/ 144.2,

[56] References Cited UNITED STATES PATENTS 1,804,628 5/1931 MacNeill 200/170 3,366,900 H1968 Barkan 335/15 FORElGN PATENTS 424,931 5/1967 Switzerland 335/195 Primary Examiner-Robert S. Macon Anorney- Flynn & F rishauf ABSTRACT: A switching device comprising a pair of bent circuit members made of flexible conductive material and arranged parallel in close proximity to each other, one of which has one of its ends electrically connected in abutting relationship to one end of at least one movable member of a pair of Y circuit switching electrodes and the other of which is pressed downward to the other end of said movable electrode by means of its operating mechanism, whereby there is generated in the paired bent circuit members a repulsive force opposing that occurring in said two electrodes at the time of conduction.

Pmzminucnsmy FIG.

PRIOR ART Toma/m VOW/l0 INVEN'I'OR.

SWITCHING DEVICE HAVING ELECTRO-MAGNETIC MEANS FOR INCREASING EFFECTIVE CONTACT PRESSURE Switch electrodes in general use are brought face to face witheach other in various forms. Among these forms, there is the so-called abutting type in which the contact plane of electrodes is made flat for mutual contact. This type is employed, for example, in a vacuum switch. In contrast to the conventional switch in which current is switched in the air, said vacuum switch is compact and of light weight due to switching being performed in a vacuum chamber. From the standpoint of constructing the vacuum chamber, the movement of electrodes is restricted, necessitating the adoption of the aforementioned abutting type of contact.

However, when the flat planes of electrodes abut against each other to introduce current, there occurs an electromagnetic force (hereinafter referred to as the first electromagnetic force" which tends to separate these electrodesfrom each other. In the case of abutting contact, electrodes land 2 are not contacted on the entire surface but approximately in spots due to the nature of materials generally constituting the parts of a vacuum switch. (FIG. l illustrates the condition where the electrodes display a spot contact at about the central part). Accordingly, current runs such a course as indicated by the dotted lines of said figure, and in the opposite planes of both electrodes there flows current in opposite directions, resulting in the occurrence of the first electromagnetic force as shown by the character A. This first electromagnetic force becomes more prominent as the passage of current increases. For example, where a switch is connected to the system in serial relationship to a circuit breaker, and said breaker cuts off a faulty current, there flows a current several times larger than the rated one. In such case, the first electromagnetic force remarkably rises. And this electromagnetic force externally acts in such a manner as to reduce the contact pressure applied to the electrodes, leading to not only an increased contact resistance, but also eventually the separation of the electrodes, in case said electromagnetic force becomes stronger than the contact pressure supplied to the electrodes, and most likely the occurrence of arcs. Such an are locally melts the contact planes of electrodes and sometimes causes the electrodes to be fused with each other, resulting in the failure of a switch to function properly. Therefore, it is necessary either to choose those materials for the contact portion of electrodes which are difficult of fusion even when exposed to arcs or always to apply externally a sufficiently great contact pressure to the electrodes.-

Nevertheless, the materials which do not easily melt upon exposure to arcs have the drawback that they do not always fully meet other properties demanded of a switch. For example, such materials cause the occurrence of chopping when a current passage is opened in a vacuum chamber, as in a vacuum switch. On the other hand, the constant external supply of great contact pressure has the disadvantage of necessarily increasing an operating power, or energy. Particularlywith a hand-operable switch, the requirement of a larger operating power would present difficulties in the handling of such switch. Then it would be inevitably required to increase the mechanical strength of the parts of such switch, causing it to have a heavier weight and need a higher manufacturing cost.

The present invention relates to improvements in a switch in which a stationary and movable electrode are made to abut against each other and more particularly to a switch which is so designed as to supply the movable electrode with a sufficient electromagnetic force to impart an elevated contact pressure to both electrodes.

The object of the present invention is to provide a switch which, to eliminate the aforementioned shortcomings of the prior art switch, comprises at least two metal conductors arranged in substantially parallel relationship and electrically connected at one end, said metal conductors being intended to supply the movable electrode with a repulsive force opposconducted and pressing a movable bar member provided with a contact plane to the stationary electrode so as to supply an increased contact pressure to both electrodes.

This invention can be more fully understood from the following detailed description when taken in connection with reference to the accompanying drawing, in which:

FIG. 1 illustrates part of the contact plane of electrodes involved in a prior art switch; and

FIG. 2 shows an arrangement forcausingswitch electrodes to contact each other according to an embodiment of the present invention.

There will now be described an embodiment of the present invention. Referring to FIG. 2, an operating lever 11 is fixed to a movable shaft 12 and rotated by an-operating mechanism (not shown). A movable electrode 13 consists of a bar 14, an insulating member 15 connected to the bottom end of said bar 14, a second conductive bar member 31 on end of which engages the insulating member 15, a first conductive bar member 17 having a substantially flat contact plane 16 formed at the bottom end, a conductor 19 assuming a stepped form like I connected at one end to a terminal conductor (not shown) through a flexible conductor 18 and held by the insulating member 15, another conductor 20 defining an opposite stepped forml to the aforementioned one and connected at one end to the first bar member 17 by suitable holding members 21 and 22 and a flexible conductor 32 for connecting the other ends (left side ends as shown) of both conductors l9 and 20 in parallel and opposite relationship. Further, the movable electrode 13 has a spring 23 positioned above the first bar member 17 and interposed between the bottom of the insulating member 15 and the top of the holding member 21 in a manner to surround the second bar member '3I. The stationary electrode 24 is provided at one end with a substantially flat contact plane 25 in a manner to face the contact plane 16 of the movable electrode I3 and at the other end connected to a terminal conductor 26. A vacuum vessel 27. is fixed to the partly indicated switch frame 28. The part of the vessel 27 which is penetrated by the stationary electrode 24 is constructed in an airtight manner, and that part of the vessel 27 which is penetrated by the movable electrode 13 is fitted with bellows 30 for allowing the vertical movement of said movable electrode 13 under airtight condition.

There will now be described the operation of a switching device according to the present invention. Let it be assumed that the lever 11 is rotated in the direction of the arrow B through the shaft 12 by an operating mechanism (not shown) and brought to a prescribed position, for example a conducting position. The spring 23 pressed by the aforesaid rotation presses the first bar member 17 downward by its elastic force, causing the-contact plane 16 of the movable electrode 13 to supply a contact pressure to the contact plane 25 of the stationary electrode 24. When, under such condition, current flows through a circuit of terminal conductor 26-stationary electrode 24-first bar member 27conductor 20-flexible conductor 32--conductor 29-flexible conductor l8-terminal conductor (not shown), then there occurs, as described above, the first electromagnetic force between the stationary electrode 24 and the first bar member 17 of the movable electrode 13, If this first electromagnetic force exceeds a contact pressure externally supplied to the movable electrode 13 it tends to separate both electrodes. Since, however,said current also travels through the conductors 20 and 19 in opposite directions, there is generated another electromagnetic force (hereinafier referred to as the second electromagnetic force) so directed as to separate both conductors 20 and 19. This second electromagnetic force acts in such a manner as to oppose the first electromagnetic force and presses the first bar member 17 downward by means of the conductor 20, thus preventing decreases in the contact pressure between both electrodes 13 and 24 caused by the first electromagnetic force on their separation.

As mentioned above, the present invention, provides a ciring that generated between both electrodes when they are cuit involving conductors arranged in approximately parallel and opposite relationship between the movable electrode 13 and conductor (not shown), thus eliminau'ng the occurrence of an increased contact resistance between both electrodes, or their separation with their resultant mutual fusion due to the generation of arcs, even when there appears the first electromagnetic force resulting from the passage of current across the movable and stationary electrodes. Moreover, where said current increases, the present invention eliminates the necessity of using larger amounts of energy in operation, so that it is particularly adapted for hand-operable switch. in addition, the present invention does not require the parts of a switch to have an increased mechanical strength, thus preventing the entire switching device from assuming a heavier weight or needing a higher manufacturing cost. Since there is no need preferentially to choose those materials for the contact portion of electrodes which are difficult of fusion particularly when exposed to arcs, the switching device of the present invention can fully meet all the properties demanded thereof.

The foregoing embodiment relates to the case where the present invention was applied to a vacuum switch. It will be apparent, however, that the invention is not limited to said switch, but is also applicable to other types.

What is claimed is:

l. A switching device including: an evacuated vessel (27);

a pair of circuit switching electrodes (17, 24,) at least one of which (17) is made movable, said electrodes having mutually facing ends (16, 25) located withinsaid vessel (27), said electrode ends 16, 25) being so arranged as to selectively abut against each other to make mutual contact;

operating means for moving said movable electrode (17) to cause said electrode ends to contact each other; and

a pair of bent circuit members (19, 20) of conductive material disposed perpendicular to the longitudinal axis of said circuit switching electrodes ('17, 24), and arranged and maintained in parallel and in close proximity to each other;

spring means (23) interposed between said bent members (19) 20) and having its force exerting axis located on the axis of movement of said movable electrode (17), said spring means (23) biasing said movable electrode (17) to exert contact pressureon said stationary electrode (24);

one of said bent members (20) being mechanically and electrically connected to a portion of said movable electrode (17) positioned outside of the vessel, and the other of said bent members (19) being coupled to said operating means such'that said other bent member (19) is pressed toward said one bent member (20) by said operating means when said switch is operated, current flowing through said bent members upon operation of said switching device causing said bent members to mutually oppose each other, thereby increasing effective contact pressure.

2. A switching device according to claim 1 comprising a flexible conductor electrically connecting said bent circuit members together.

3. A switching device according to claim 1 wherein said bent members are disposed within a parallel plane-arranged perpendicular to the longitudinal axis of said circuit switching electrodes. I

4. A switching device according to claim 1 wherein said bent members have oppositely disposed, generally stepped forms (I).

5. A switching device according to claim 3 wherein said movable electrode includes an elongated member (17), said operating means includes a rod (31) interposed between said bent circuit members (19, 20) with its longitudinal axis aligned with that of said elongated member (17) and being operatively coupled to said elongated member (17), and said spring means (23) is a coil spring mounted around said rod 

1. A switching device including: an evacuated vessel (27); a pair of circuit switching electrodes (17, 24,) at least one of which (17) is made movable, said electrodes having mutually facing ends (16, 25) located within said vessel (27), said electrode ends (16, 25) being so arranged as to selectively abut against each other to make mutual contact; operating means for moving said movable electrode (17) to cause said electrode ends to contact each other; and a pair of bent circuit members (19, 20) of conductive material disposed perpendicular to the longitudinal axis of said circuit switching electrodes (17, 24), and arranged and maintained in parallel and in close proximity to each other; spring means (23) interposed between said bent members (19) 20) and having its force exerting axis located on the axis of movement of said movable electrode (17), said spring means (23) biasing said movable electrode (17) to exert contact pressure on said stationary electrode (24); one of said bent members (20) being mechanically and electrically conNected to a portion of said movable electrode (17) positioned outside of the vessel, and the other of said bent members (19) being coupled to said operating means such that said other bent member (19) is pressed toward said one bent member (20) by said operating means when said switch is operated, current flowing through said bent members upon operation of said switching device causing said bent members to mutually oppose each other, thereby increasing effective contact pressure.
 2. A switching device according to claim 1 comprising a flexible conductor electrically connecting said bent circuit members together.
 3. A switching device according to claim 1 wherein said bent members are disposed within a parallel plane arranged perpendicular to the longitudinal axis of said circuit switching electrodes.
 4. A switching device according to claim 1 wherein said bent members have oppositely disposed, generally stepped forms ( ).
 5. A switching device according to claim 3 wherein said movable electrode includes an elongated member (17), said operating means includes a rod (31) interposed between said bent circuit members (19, 20) with its longitudinal axis aligned with that of said elongated member (17) and being operatively coupled to said elongated member (17), and said spring means (23) is a coil spring mounted around said rod (31). 